1. Technical Field
The invention relates to an optical module. Particularly, the invention relates to a backlight module applied to a display device.
2. Related Art
Along with development of display technology, flat panel displays gradually replace conventional cathode ray tubes (CRTs) and become a main stream in display market. In the flat panel displays, liquid crystal displays (LCDs) are most popular. A general LCD is mainly composed of a backlight module and an LCD panel. Since the LCD panel is not luminous itself, the backlight module is used to provide a planar light source required for display.
Generally, the backlight modules are mainly divided into direct type backlight modules and side type backlight modules. Taking the side type backlight module as an example, the side type backlight module generally includes a light guide plate (LGP), a light source disposed at a light incident surface of the light guide plate and an optical film disposed at a light emitting surface of the light guide plate. Based on a total reflection principle, a light beam emitted by the light source is guided to the whole light guide plate after entering the light guide plate through the light incident surface. According to the existing technique, a plurality of microstructures are configured on a bottom surface of the light guide plate to spoil the total reflection of the light beam, such that the light beam emits out from the light emitting surface of the light guide plate. The light beam emitted from the light emitting surface further passes through the optical film disposed on the light guide plate to form the planar light source required by the display panel.
However, along with breakthrough of process technology, light emitting diodes (LEDs) gradually replace cold cathode fluorescent lamps (CCFL) to serve as the light source in the backlight module. According to the existing design, a plurality of LEDs are arranged beside the light incident surface of the light guide plate in intervals. However, light intensities of the LEDs serving as point light sources are not evenly distributed on the light incident surface, where regions on the light incident surface corresponding to the LEDs may form bright zones, and dark zones are formed on the light incident surface corresponding to regions between the LEDs, such that the planar light source output by the light guide plate may have a mura phenomenon. In other words, the side type backlight module using the LEDs as the light sources may have a problem of uneven emitted light in an actual application. Therefore, how to resolve the above problem is an important issue concerned by related technicians.
Taiwan Patent No. 1375822, M264503, 1296694, M264504 and Taiwan Patent Publication No. 201344307 respectively disclose a plurality of microstructures of the light guide plate, which are used for spoiling the total reflection of light to enhance a light usage rate. Taiwan Patent No. 1301920, 1388891, 1407162, China Patent No. 102155711 and U.S. Pat. No. 736,341 respectively disclose a plurality of microstructures of the light guide plate, which are used for improving light diffusibility and mitigating uneven light intensity and the mura phenomenon.
The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.